For me, my favorite presentation is always the one I am currently working on. In this case, it is applying the Brainwave Principle to a deck of blank-both-sides playing cards. My presentation is described at The Magic Nook in The Wizards' Journal #38 under the name "Blankety-Blank Cards". After the blank deck is shuffled by spectators (and therefore examined without saying so), two cards are freely named along with the color back of the imagined card (red or blue). The card then appears in the blank deck and shown both front and back to be exactly as imagined. The second card chosen (front and back) appears among the blank cards as the spectator is dealing out blank cards to another spectator, so it happens right in the hands of the spectator. https://www.magicnook.com/WizJournal/WJ-38ALL.htm ... if you need help finding it. Scroll down to item 10.

This is a three deck trick. One is the Brainwave (or Ultramental), the other two are normal. This is based on the idea that if two people, each with a deck, deal cards face up simultaneously, you will virtually always get a match somewhere. Then turn this into a 3-way 'coincidence' by revealing the same card with your gaff deck. (!)

I present it as a straight mentalism effect - specifically, as an experiment in mental telepathy. A sealed envelope is introduced and given to a spectator to hold. I tell the spectator that I am going to attempt to telepathically communicate to him or her the name of a certain playing card from a deck of cards, but the card will not be a joker. The spectator is then asked to think of a card. From the spectator's point of view, there is apparently no way I could ascertain or know the identity of the thought-of card. Subsequently, the sealed envelope is taken back from the spectator, and ripped open. Inside is a deck of cards (no box). The cards are spread to show there is a single card face up among the otherwise face-down deck. It is the thought-of card, and the spectator attests to this. The back of the card is then shown to be a different color back from all the other cards in the spread. At no time prior to the revelation do I ask the spectator to state the identity of the thought-of card. (Note: In the unlikely event the spectator decides to think of the joker despite the fact that I said it would not be the card I would mentally transmit, i have an out, and the effect will be no less astonishing)